[Coco] DW4 Nitros9 and floppy disk access

[Gene Heskett]

On Sunday 13 January 2019 09:13:54 Walter wrote:

> Some more info.
>
> With the miniFlASH in slot 3 and the FD-502 in slot four.
>
> If I start the CoCo with the MPI selector set to slot 3 I get the
> behaviour described before.
>
> If I set the MPI to slot 4 then I get the DECB and I can access the
> floppy but HDB-DOS does not start. But I suppose this is to be
> expected.
>
> If I start the MPI on slot 3 again and after HDB-DOS has started I
> change the MPI selector to slot 4 I can access both DriveWire and the
> floppy drive.  Now we're talking!
>
> However I'm not sure I like changing the MPI selector while it is on!
>
> Is there a way I can do this via software?
>
> And one last thing.  Only the real Tandy floppy drive works my crazy
> Chinon floppy drive doesn't work! I can hear the Chinon floppy trying
> to read but it just re-attempts several times and then errors.

Potential trivia fact for the day.

That Chinon drive may have been rescued from an Amiga computer, whose 
floppy drives contained no index pulse generator because the amiga 
floppy access was via trackdisk, reading, and writing a whole track at a 
time. Because it was a read-modify-write setup, it could start reading a 
track at any point in the disks rotation, would then search the track 
buffer for the needed info, and conversely could start a rewrite of the 
track at any rotational point in the disks rotation. So it needed no 
index pulse to synchronize the data to a fixed location on the disk, and 
Commode Door was cheap & sleazy enough to make Chinon leave those 30 
cents worth of parts out.

Cheers, Gene Heskett
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